LINCOLN, Nebraska (CNN) -- The troubled teen who killed eight people and himself at an Omaha, Nebraska, mall was placed in a mental health treatment center five years ago after making homicidal threats toward his stepmother, a state official said Thursday.

Todd Landry, director of the Nebraska Division of Family and Children's Services, described for reporters the laundry list of residential treatment centers and group and foster homes where Robert Hawkins spent much of his teen years, because of his behavioral and psychiatric problems.

At one point during that period Hawkins also filed a report with police alleging he was molested by a roommate at one of the facilities. The case was resolved internally, according to the report.

Asked about the allegation, Landry responded, "I can't confirm or deny that that may have happened."

Hawkins was sent to Piney Ridge Center in Waynesville, Missouri, on May 18, 2002 -- a day after his 14th birthday. The center specializes in mental health and substance abuse services, according to its Web site.

Landry, reading from a juvenile court petition filed by Sarpy County, Nebraska, said Hawkins was placed at the center because of "homicidal threats to his stepmother."

"He also had two psychiatric hospitalizations, and has been diagnosed with attention deficit disorder, mood disorder, oppositional defiant disorder, and parent-child relationship problems," Landry said.

He offered no details about the problems with the stepmother.

When the teen went to live with friends of the family one and a half years ago, "issues with the stepmother" were the reason, said Debora Maruca-Kovac, into whose house he moved. Watch her describe their last conversation »

Landry divulged only information from public records, as allowed by law.

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Hawkins was a ward of the state from September 17, 2002, through August 24, 2006. Parental rights were never severed, authorities said.

Among the problems cited in the records were his involvement in a fight and substance abuse problems.

Nebraska court records show a Hawkins with a matching age had a juvenile criminal history including charges of alcohol and drug use, disorderly conduct and contributing to the delinquency of a minor. He is listed in the records as living with a foster parent.

According to Landry, Hawkins' treatments were extensive, and cost the state $265,000 while he was in its custody.

"This tragedy was not a failure of the system to provide appropriate quality services for a youth that needed it," he said.

Maruca-Kovac described Hawkins on CNN's "Anderson Cooper 360" Wednesday night as "kind of like a pound puppy that nobody wanted."

Paraphrasing a suicide note he left in their home, she said, "He didn't want to be a burden to people and [said] that he was a piece of s--- all of his life and that now he'd be famous." Watch officials detail the rampage »

Hawkins' body was found on the third floor of the Von Maur store inside Westroads Mall. Police believe the attacks were premeditated, but the victims were targeted at random.

Omaha Police Chief Thomas Warren said Hawkins visited with a friend before going to the mall, and he sent a text message to a girl, apparently a recent ex-girlfriend. He also left voicemail for his mother, Warren said.

Maruca-Kovac told CNN Hawkins left the house Wednesday about 11 a.m., and called her about two hours later, sounding upset.

"He just said he wanted to thank me for everything I'd done for him ... and he was sorry," Maruca-Kovac said. He told her he had been fired that day from his job at McDonald's, she said. See a map of where the shooting took place »

"I said, 'Come home and we'll talk about it.' "

"He said, 'It's too late.' He said he'd left a note explaining everything."

The suicide note left at Maruca-Kovac's home was turned over to police, who wouldn't divulge its contents.

"He basically said how sorry he was for everything," Maruca-Kovac told CNN on Wednesday night. She described Hawkins as well-behaved, although "he had a lot of emotional problems, obviously."

This past summer, Hawkins tried to enlist in the U.S. Army but was turned down, a source familiar with the situation told CNN. The source didn't want his name used because revealing information about potential recruits is against military rules.

The two recruiters who spoke with Hawkins said he appeared to be a typical teenager.

"He said he'd had a rough time in his life and wanted to see about changing it," Army Sgt. Edward Dust said.

Hawkins had been on antidepressants but stopped taking them because they made him feel "weird," Maruca-Kovac said. There was no public information on how long he had been off the medication or what the medication was.

When Hawkins moved in with Maruca-Kovac's family, Maruca-Kovac said, he felt mistreated and rejected by everyone. He also suffered from depression.

"When he first came and lived with us, he was in the fetal position and chewed his fingernails all the time, and was unemployed, and hopeless. After awhile, he got a job and came out of that," Maruca-Kovac told CNN. He also got a haircut, and seemed happier, she said.

She said she was unaware Hawkins had any guns, although she said he knew a lot about them, as did his stepfather. Although police haven't completed tracing the weapon Warren said police believe Hawkins stole the firearm, which was stored at his stepfather's residence. Warren said it was an "AK-47 assault weapon."

He added, "I'm not sure the level of depression, I just know he was on antidepressants the last couple of months. I guess it was just getting worse over time with the loss of his job and I guess issues he had going on with the girlfriend at the time."E-mail to a friend